Floating barrel action for automatic pistol



Aug- 12 1958 'Y 'J. w. KIMBALL 2,846,926

FLOATING BARREL ACTION FOR AUTOMATIC PISTOL Filed Dec. 14. 1954 l 2 Sheets-Sheet 1 Fl 1 I4 34 I8 1N VEN TOR.

' A TTONEYS Aug. 12, 1958r J. w. KIMBALL 2,846,926

FLOATING BARREL ACTION FOR AUTOMATIC PISTOL Filed Deo. 14, 1954 2 Sheel'.S-She e`1l 2 IN VEN TOR.

UWM/:Kimball HTTdE/VEYS United States Patent O FLOATING BARREL ACTION FOR AUTOMATIC PISTOL The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to recoil operated firearms of the blowback type and is more particularly directed to improved means for effecting the necessary delay in the opening of the breech.

In the blowback system of firearm operation, the breech is not positively locked at the instant the cartridge is tired. Instead, the weightA of the recoiling parts and the force of the return springs are Vcombined to delay the opening of the breech until the bullet has cleared the muzzle end of the barrel and permitted the chamber pressure to drop to a comparatively safe level. Recoil actions of the blowback type have proven highly satisfactory and reliable in those iirearms wherein the inertia of the recoiling parts necessary to delay the opening of the breech can be readily attained with a bree'chblock of reasonable mass. However, when the ammunition employed is capable of developing chamber pressures in excess of 5000 p. s. i., the necessary increase in the weight of the breechblock renders the iirearmimpractical from the standpoint of ease of handling and accuracy of fire.

Attempts to reduce the weight of the recoiling parts have usually resulted in premature openings of the breech with the attendant danger of ruptured' cartridge cases. This malfunction is due to the rearward movement imparted to the unsupported rear end of -the cartridge case by the expansion of the discharge gases while the front end of the case is still being tightly gripped by the walls of the tiring chamber in the barrel. Although the possibility of ruptured cartridge cases can bek appreciably reduced by adequate reinforcement of the neck portion thereof or by proper lubrication prior to chambering, such expedients are expensive and time-consuming and, at best, merely provide a marginal factor of safety.

Accordingly, it is an object of this invention to provide a novel means for delaying'the opening of the breech in rearms having a recoil :action of the blowback type.

It is another object of this invention to appreciably reducefthe weight of the breehblock in a firearm recoil.` aetinr Lqt2 the bleu/hack, type. withont, ingurringthe .attendant danger of pre-mature opening of they breech@ t., wm-W, t sfilialiafharshiataqf ,thelrresentl inuentinnflieslnpmdan tot @firearm otrdieblow.-j

actions of 2,846,926 Patented Aug. 12, 1958 tion. Inasmuch as appreciable variation is often encountered in the gas pressures developed by the commercial ammunition furnished for these light weapons, the weight of the recoiling parts is customarily maintained at the minimum side of the permitted tolerance in order to insure positive operation at all times. As a result, the recoil energy ordinarily transmitted to the hand of the operator is sufficient to make the weapon relatively unpleasant to tire. Moreover, in theevent a particular lot of ammunition should develop maximum chamber pressures or in the event it is desired to utilize relatively highpowered rifle ammunition, the excessive recoil energies produced thereby would disturb the effective accuracy of a hand-operated firearm such as a pistol when ernployed in rapid lire or in the hands of an inexperienced marksman who is apt -to iiinch in response to an lappreciable recoil shock.

It is, therefore, :another object of this invention to provide a blowback type of recoil action for s'emiautomatic pistols which will provide improved accuracy of tire and rapidity of operation.

A speciiic object of this invention is to provide an improved blowback type of recoil mechanism for a semiautomatic pistol wherein the components vthereof are relatively few in number, easy to manufacture, light in weight, and yet are eiective and efficient in providing a substantial delay in the opening of the breech even when firing relatively high-powered ammunition.

The invention essentially proposes the use yof a free recoiling barrel as one of the components in a recoil action for a` rearm of the blowback type. The tendency of cartridge cases to adhere to the walls of the firing chamber under the relatively high gas pressures which exist therein is utilized to couple the barrel to the breechblock and thereby delay the opening of the breech until the pressure has been dropped to a comparatively safe level.

The speciiie nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

n Fig. l is a side elevational view of a semiautomatic pistol partially cut away to show the relative position of the recoiling parts and of the operating and ejection springs at the instant of tiring. v

Fig. 2 is a view similar to Fig. 1 but on an enl-arged scale showing the relative position of the recoiling parts immediately prior to the opening of the breech;

Fig.Y 3 is a view similar to Fig. 2 but showing the relative position of the parts immediately prior to ejection of a fired cartridge case;

Fig. 4 is a front elevational view of the pistol to which the present invention is adapted with the barrel and buffer tube removed to showA the face of the slide; I!

Fig. 5 is a fragmentary side elevational View of the forward section' of th'epistol; Iand v i Figw is an; exploded perspecti Vview showing the individual; parte er are b'nef'tuae ssefriuyff fAlt-houg'h' the Ipresentiriven'tioril Eis" de's'c/'ribe'dwv' ring pin 18, a pivotal extractor 19 and an ejector 29 biased forwardly by a spring 21.

For the purposes of the present invention, however, barrel 14 is slidably mounted in frame 12 Moreover, frame 12 is.provided with arearwardly `extending longitudinalhole 22A bel-ow barrel 14 and substantially parallel thereto in which a cylindrical buffer tube 23 is xedly ,securedat a point adjacent the rear end thereof as by a transverse pin 24. Tube 23 is a hollow member closed at the front end as indicated at 25 and mounted within the interior thereof is a spring 26 whose end coils surround the opposed stem portions 27 of a pair of headed pins 28. A plug 29 is preferably threaded into the open rear end of tube v23 to form a xed bearing surface for the rearward one of pins 28. An elongated slot 30 is formed along the top of buffer tube 23 to receive a lug 3,1 which depends from the underside of barrel 14 and forms a bearing surface for the forward one of pins 28. Whilethe means for returning barrel 1'4 to battery position is illustrated and described as a separate assembly located below barrel 14, it should be understood that the present invention is not limited thereto but is also intended to include any type of mechanism and location therefor which will effect counterrecoil movement of barrel 14.

` When the recoiling parts are in battery, barrel 14 is held in its extreme forward position by the bias of spring 26 against lug 31 while at the same time a conventional recoil spring 32 urges slide 13 forwardly against the breech end of barrel 14 in which a cartridge had been chambered during the previous operating cycle. When the. pistol is tired by the release of firing pin 18 from its cocked position, the rapidly expanding discharge gases act upon the interior walls of the tired cartridge case 33 to press the exterior surfacethereof tightly against the walls of tiring chamber 17 in barrel 14. The expansion of the walls of the red cartridge case occurs so quickly, especially when relatively high-powered ammunition is employed, that the freezing action thereof in barrel chamber 17 is substantially completed even. before slide 13 overcomes the inertia resistance thereof and begins to recoil.

Since the fired cartridge case is rendered practically immovable in tiring chamber 17, the recoil momentum of slide 13 is in turn imparted to barrel 14 through the medium ofV the engagement between extractor 19 and the fired cartridge case so that both components move rearwardly together.

If barrel 14 were fixed as in conventional blowback types of firearms, the rearward acceleration of slide 13 i would initiate extraction of the fired case 33 from tiring chamber 17 before the bullet 34 had cleared the muzzle end of barrel 14. Under these conditions, the existing high gas pressure would continue to hold the forward end of the red cartridge case 33 firmly against the interior wall surfaces of chamber 17 while the rear end thereof was being pulled rearwardly by extractor 19 on the recoiling slide 13, thereby rupturing the fired case whenever the metal thereof was stretched beyond its elastic limit. However, inasmuch as barrel 14 is here free to move rearwardly in frame 12 and recoils together with slide 13, there is no appreciable movement of the fired cartridge case 33 in ring chamber 17 until the chamber pressure has been considerably reduced.A It is, therefore, apparent that the weight of barrel 14 and the resistance of spring 26 act to reduce the recoil energy imparted to slide 13 and thereby compensate for the reduced weight thereof. When the bullet 34 clears the muzzle end of barrel 14, the residual gas -pressure continues to hold cartridge case 33 in chamber 17 until lapproximately the instant barrel 14 reaches the limit of its recoil movement. The disengagement of barrel 14 from ired case 33 and the consequent transition from i recoil to counter-recoil movement ordinarily occurs prior to any contact between the oppositely facing stem por- 4. tions 27 Y of, flanged pins 28. However, in the event the gas pressure in tiring chamber 17 exceeds the normal amount for which the recoil action is designed, the eventual contact between headed pins 28 will halt the recoil of barrel 14. The resulting impact will break the grip between the ired'cartridge case 33 and the walls of tiring chamber 17 without imparting any noticeable jar to the hand ofthe tirer since theimpact transmitted through transverse pin 24 isabsorbed by the relatively heavy mass of frame 12. j

Furthermore, even if the chamber pressure was unusually high at the termination of the recoil movement of barrel 14, the sudden stop thereof and the accompanying momentum imparted to slide 13 would still be suf cient to breakthe engagement of case 33 in chamber 17. Moreover, it will be apparent that any frictional resistance between the exterior of case 33 and the walls of chamber 17 which did occur during extraction would simultaneously provide a desirable decrease in the recoil energy imparted to slide 13. A

When barrel 14 is uncoupled from slide 13 by the disengagement of the red cartridgeV case 33 from ring chamber 17, the counterrecoil movement imparted to barrel 14 by the expansion of spring 26 against-depending lug 31 is Veventually halted bythe contactV thereof with the front closure 2S of buffer tube 23. Since the impact therebetween occurs while slide 13 is still recoiling to complete `extraction and ejection of the'red cartridge case 33 as shown in Fig.n3, it can be readily seen that such impact acts to reduce any recoil movement which may have been transmitted to frame 12 and thereby to the hand of the tirer. The recoil energytransmitted to vslide 13 by the ring of a cartridge is still further reduced throughout its entire wtravel by the compression of operating spring 32. Moreover, ras slide 13 reaches the end of its recoil movement, the compression of ejector spring 21 serves as an additional Vmeans for absorbing the remaining recoil energy ofl slide 13 and thereby pre1 venting any undesirable impact thereof against the rear end of frame-1 2. The subsequent counterrecoil movement of slide 13 chambers a fresh cartridge into firing chamber 17 of barrel-14 in the usual way.

Thus, there is here provided a novel means for effecting an appreciable delay in the opening of the breech in a simpleblowback type of `recoil action Vwhich does not depend on the inertia weight of the breechblock alone. As a result, this invention permits the advantages of simple blowback actions tov be incorporated in muchheavier weapons than heretofore deemed practical. In addition, the use of the blowbackfaction of the present invention in firearms such as pistols produces a surprising decrease in the recoil movement imparted tothe hand of the marksman and, therefore, increases the accuracy of the Weapon as well as the rapidity'with which it can be'red even when chamber pressures up to 50,000'p. s. i. are developed. These advantages are due primarily to the fact that the addition of the barrel to the recoiling parts of a pistol permits a corresponding reduction in the weight of the slide without subjecting the' action to dangerous premature openings of the breech." v

Furthermore, this invention is particularly adapted to permit the tiring of cartridges of considerably higher power thanthose normally employed in semiautomatic pistols and submachine guns. In fact, the extensive testing carried "out during the development of the present invention has indicated that even when relatively highpowered rie ammunition such as Cal. .22 Hornet or U. S. Cal. .30 M1 carbine cartridges are red in the semiautomatic pistol described herein, the action is still capable of absorbing the correspondingly high recoil'energies smoothly and effectively.

Although a particular embodiment of the invention has been described in detail herein, it is evidentl that many variations may be devised within` the spirit` and scope thereof and the following claims are intended to include such variations.

I Claim:

l. In a firearm having a receiver, a recoiling barrel having a cartridge chamber therein and being slidably mounted in the receiver for reciprocal movement from and toward a fully forward battery position, a breechblock slidably mounted in the receiver for recoil movement in response to the firing of a cartridge, said breechblock and said barrel being unlocked relative to the receiver and to each other at the instant prior to the discharge of the cartridge and being structurally independent 0f each other during the entire reciprocal movements thereof, extractor means in the forward end of said breechblock for gripping the rear end of the cartridge whereby the pressure of the expanded walls of the fired cartridge case against the interior surfaces of said barrel chamber couples said barrel to said breechblock to lock the breech for a limited interval of time dependent on the degree of chamber pressure generated by the firing of the cartridge, and resilient means operative upon disengagement of the red cartridge case from said chamber to return said barrel to the battery position thereof While said breechblock continues to recoil.

2. In a semiautomatic pistol, a fixed frame, a recoiling barrel slidably mounted in said frame, a slide reciprocably mounted in said frame for movement from and toward a fully forward battery position, an operating spring normally urging said slide to the battery position thereof, said slide and said barrel being unlocked relative to said frame and to each other at the instant prior to the discharge of the cartridge and being structurally independent of each other during the entire reciprocal movements thereof, means in the forward end of said slide for gripping the base of the cartridge whereby said barrel is coupled to said slide to lock the breech during the interval in which the gas pressure generated by the ring A of the cartridge expands the walls thereof into nonslip-` ping engagement with the interior bore surface of said barrel, and resilient means operative upon disengagement of the red cartridge case from said chamber to return said barrel to the prefired position thereof, said barrel having a mass calculated to reduce the recoil momentum of said slide to the extent necessary to prevent any impact thereof on said frame until after the return of said barrel to the battery position.

3. In a semiautomatic pistol having a fixed frame, a recoiling barrel having a tiring chamber therein and being slidably mounted in the frame for movement from and toward a fully forward battery position, a hollow buier tube xedly secured in the frame below said barrel, a slide reciprocably mounted in the frame for recoil and counterrecoil movement, an operating spring disposed in said slide to resist the recoil movement thereof, said slide and said barrel being unlocked relative to said frame and to each other at the instant prior to the discharge of the cartridge and being structurally independent of each other during the entire reciprocal movements thereof, an extractor ymounted in the forward end of said slide for gripping the rear end of the cartridge whereby the chamber pressure generated upon the firing of the cartridge expands the walls thereof into gripping engagement with the interior surfaces of said barrel chamber to couple said barrel to said slide and thereby lock the breech until the chamber pressure falls below the level necessary to prevent movement of the fired cartridge case in said barrel chamber, said barrel having sufficient mass to assist in reducing the recoil momentum imparted to said slide in order to lessen the expected impact thereof on said frame at the conclusion of recoil movement, said barrel having a depending lug extending 'into the interior of said hollow tube, and spring means seated between the rear end of said tube and the rear surface of said depending lug for returning said barrel to the battery position thereof while said slide continues to recoil.

4. ln a semiautomatic pistol, a fixed frame, a ho-llow buffer tube having a longitudinal slot in the top thereof, pin means for xedly securing said bulfer tube in said frame to project forwardly therefrom, a recoiling barrel slidably mounted in said frame above said hollow tube for reciprocal movement between a battery and a recoil position, said barrel having a cartridge chamber in the rear end thereof and a depending lug extending through said slot in said buffer tube to terminate within the interior thereof, a slide reciprocably mounted in the frame for recoil and counterrecoil movement, an operating spring disposed between said frame and said slide to impart countercoil movement to the latter, said slide being unlocked in relation to both said frame and said barrel at the instant prior to the firing of the cartridge, said slide and said barrel being structurally independent of each other'throughout the entire recoil movement thereof, an

extractor mounted in the forward end of said slide for gripping the rear end of the cartridge whereby the chamber pressure generated upon the firing thereof expands the walls into nonslipping engagement with the interior surfaces of said barrel chamber to couple said barrel to said slide and thereby lock the breech during the initial portion of recoil until the decreasing chamber pressure permits extraction movement of the red cartridge case in said barrel chamber, a pair of oppositely-facing headed pins disposed in said buffer tube between the rear end thereof and said depending barrel lug to limit the recoil movement of said barrel, anda spring seated between said pins to return said barrel to battery position thereof prior to the counterrecoil movement of said slide whereby the impact of said depending barrel lug against the forward end Wall of said buffer tube counteracts the subsequent recoil momentum imparted to said frame by said slide.

n References Cited in the le of this patent UNITED STATES PATENTS 684,055 Fairfax Oct. 8, 1901 743,002 Knoble Nov. 3, 1903 1,455,880 Hammond May 22, 1923 2,146,185 Holek Feb. 7, 1939 2,370,363 Lippert Feb. 27, 1945 2,557,134 Mudespacher June 19, 1951 2,705,847 Kramer Apr. 12, 1955 

